CN109841743B

CN109841743B - Transparent conductive oxide coatings for organic light emitting diodes and solar devices

Info

Publication number: CN109841743B
Application number: CN201910282487.XA
Authority: CN
Inventors: A·布翰达利; J·W·麦卡米
Original assignee: Vitro SAB de CV
Current assignee: Vitro SAB de CV
Priority date: 2013-03-12
Filing date: 2014-03-11
Publication date: 2022-12-27
Anticipated expiration: 2034-03-11
Also published as: US9444068B2; US20140312327A1; EP2973776B1; MY168736A; JP6462656B2; KR20170077265A; JP2016515294A; KR20150118971A; CN105453293A; WO2014164580A1; TW201507229A; KR101751884B1; KR101787957B1; CN105453293B; JP2018152358A; TWI577068B; CN109841743A; EP2973776A1

Abstract

A Transparent Conductive Oxide (TCO) electrode for an Organic Light Emitting Diode (OLED) has a first layer of crystalline material and a second layer of amorphous material. The material of the second layer may comprise one or more dopant materials.

Description

Transparent conductive oxide coatings for organic light emitting diodes and solar devices

The application is a divisional application with the application date of 2014, 3, 11, and the application number of 201480014699.5, and the invention name of the application is 'transparent conductive oxide coating for organic light-emitting diodes and solar devices'.

Cross Reference to Related Applications

This application claims priority to U.S. provisional application No.61/777,251, filed on 12.3.2013, which is hereby incorporated by reference in its entirety.

Background

Technical Field

The present invention relates generally to organic light emitting diodes, solar or Photovoltaic (PV) cells, and more particularly to electrode structures for such solar devices providing improved manufacturing and operating performance.

Technical considerations

Organic Light Emitting Diodes (OLEDs) are light emitting devices having an emissive electroluminescent layer incorporating organic compounds. The organic compound emits light in response to an electric current. Typically, an emissive layer of organic semiconductor material is located between two electrodes (an anode and a cathode). In many conventional OLEDs, the cathode is typically an opaque metal layer and the anode is formed from a Transparent Conductive Oxide (TCO) layer. The anode is transparent to allow light to exit the OLED. When an electric current is passed between the anode and the cathode, the organic material emits light. OLEDs are used in many applications such as television screens, computer monitors, mobile phones, PDAs, watches, lighting devices and various other electronic devices.

Photovoltaic solar cells are in principle the counterparts to light emitting diodes. Here, the semiconductor device absorbs light energy (photons) and converts the energy into electricity. Similar to OLEDs, solar cells typically incorporate TCO electrodes.

In both OLEDs and solar cells, the TCO electrode should have certain properties. For example, the TCO electrode should have high visible light transmittance. Furthermore, the TCO electrode should have a low sheet resistance (high conductivity). TCO conductivity can generally be achieved by using an oxide coating doped with a conductive material. The higher the dopant level, the lower the sheet resistance. However, increasing the dopant level decreases visible light transmission.

TCOs are typically crystalline materials because crystalline materials tend to be more conductive than amorphous materials and also require a lower "onset voltage" than amorphous materials. However, crystalline materials have a problem in that their surface roughness is higher than that of amorphous materials due to their crystalline structure. If this surface roughness is too high, the crystals of the crystalline TCO anode can extend through other layers of the OLED device and can contact the cathode, causing an electrical short.

It would therefore be advantageous to provide an electrode structure for use with an OLED or solar cell that helps to reduce the likelihood of electrical shorts and/or lower the start-up voltage of the device and/or maintain a desired level of conductivity.

Disclosure of Invention

The light emitting device includes a substrate, an emission layer, a first electrode, and a second electrode. At least one of the first and second electrodes comprises a composite TCO electrode comprising a first layer comprising a crystalline material and a second layer comprising an amorphous material.

Another light emitting device includes a substrate, an emission layer, a first electrode, and a second electrode. At least one of the first and second electrodes comprises a composite TCO electrode comprising a first layer comprising an oxide material, optionally a second layer comprising a metal material, and a third layer comprising an oxide material.

The oxide materials of the first and third layers are independently selected from one or more oxides of Zn, fe, mn, al, ce, sn, sb, hf, zr, ni, zn, bi, ti, co, cr, si, in or alloys of two or more of these materials, such as zinc stannate. The first and/or third layer may be doped or undoped.

In one aspect of the invention, the second layer is absent, the first layer comprises a doped oxide material, and the third layer comprises vanadium doped indium oxide.

In another aspect of the invention, the first layer comprises zinc-doped indium oxide, the second layer is present, and the third layer comprises zinc-doped indium oxide.

In another aspect of the invention, the first layer comprises a doped oxide, the second layer is present, the third layer comprises titanium, and the composite TCO electrode further comprises a fourth layer on the third layer, and the fourth layer comprises an oxide material or a doped oxide material.

In another aspect of the present invention, the first layer comprises IZO and/or the second layer comprises silver and/or the fourth layer comprises zinc oxide and/or the fifth layer is present on the fourth layer, and the fifth layer comprises IZO.

The composite TCO electrode may include a first layer comprising a doped oxide; a second layer comprising a metallic material; and a third layer comprising IZO, wherein the IZO is deposited in two layers, and the bottom layer is deposited under a higher oxygen atmosphere than the top layer.

The composite TCO electrode may include a first layer comprising an oxide selected from ITO and IZO; a second layer comprising a metallic material; a third layer comprising ITO; and a fourth layer including a material selected from IZO, alumina, silica or a mixture of alumina and silica.

The composite TCO electrode may include a first layer comprising zinc oxide; a second layer comprising a metallic material; and a third layer comprising alumina, silica, or a mixture of alumina and silica.

The composite TCO electrode may include a first layer comprising zinc oxide; a second layer comprising a metallic material; and a third layer comprising IZO.

The composite TCO electrode can include a first layer of an oxide material including zinc and tin; a second layer comprising a metallic material; a third layer comprising titanium; and a fourth layer comprising an oxide material comprising zinc and tin.

The composite TCO electrode includes a first layer including a crystalline material and a second layer including an amorphous material.

The material of the second layer may comprise one or more dopant materials. The material for the first and/or second layer may be selected from one or more oxides of Zn, fe, mn, al, ce, sn, sb, hf, zr, ni, zn, bi, ti, co, cr, si, in or alloys of two or more of these materials, such as zinc stannate. The material of the second layer may comprise one or more dopants.

The material for the first and/or second layer may be selected from fluorine doped tin oxide, zinc doped indium oxide, indium doped tin oxide, tin doped indium oxide and oxides of zinc and tin (such as zinc stannate).

The first layer may comprise a doped metal oxide material and the second layer may comprise vanadium doped indium oxide.

Another composite TCO electrode includes a first layer including a metal layer and a second layer including an oxide material.

The metal layer may be selected from platinum, iridium, osmium, palladium, aluminum, gold, copper, silver, or mixtures thereof.

Another composite TCO electrode includes a first layer including an oxide material, a second layer including a metal material, and a third layer including an oxide material.

The third layer may comprise an amorphous material.

Still another composite TCO electrode includes a first layer comprising a doped oxide material and a second layer comprising vanadium doped indium oxide.

Another composite TCO electrode includes a first layer comprising zinc-doped indium oxide, a second layer comprising a metal material, and a third layer comprising zinc-doped indium oxide.

Another composite TCO electrode includes a first layer including a doped oxide, a second layer including a metal material, a third layer including titanium, and a fourth layer including a doped oxide.

The first layer may be IZO, the metal layer may be silver, and the fourth layer may be IZO.

Still another composite TCO electrode includes a first layer comprising a doped oxide, a second layer comprising a metal material, a third layer comprising Indium Zinc Oxide (IZO), wherein IZO is deposited in two layers, and the bottom layer is deposited under a higher oxygen atmosphere than the top layer.

Another composite TCO electrode includes a first layer including an oxide selected from Indium Tin Oxide (ITO) or IZO, a second layer including a metal material, a third layer including ITO, and a fourth layer including IZO.

Another composite TCO electrode includes a first layer comprising an oxide selected from ITO and IZO, a second layer comprising a metal material, a third layer comprising ITO, and a fourth layer comprising alumina, silica, or a mixture of alumina and silica.

Still another composite TCO electrode includes a first layer comprising zinc oxide, a second layer comprising a metal material, and a third layer comprising alumina, silica, or a mixture of alumina and silica.

Another composite TCO electrode includes a first layer comprising zinc oxide, a second layer comprising a metal material, and a third layer comprising IZO.

Additional composite TCO electrodes include a first layer comprising an oxide material (which includes zinc and tin), a second layer comprising a metal material, a third layer comprising titanium, and a fourth layer comprising an oxide material (which includes zinc and tin).

A method of increasing light scattering of a device having a glass substrate comprises: roughening the glass surface; and applying a planarization layer onto the roughened surface, followed by forming an additional coating layer on the surface.

Drawings

FIG. 1 is a side cross-sectional view (not to scale) of an OLED device incorporating the composite TCO of the present invention;

FIGS. 2-11 are various composite TCO electrode structures (not to scale) incorporating features of the invention; and

figure 12 illustrates the use of a planarization layer (not to scale) according to the present invention.

Detailed Description

As used herein, spatial or directional terms, such as "left", "right", "inside", "outside", "above", "below", and the like, relate to the invention as it is shown in the drawings. It is to be understood, however, that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, as used herein, all numbers expressing dimensions, physical characteristics, processing parameters, ingredient contents, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims can vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical value is at least interpreted in light of the number of reported significant digits and by applying ordinary rounding techniques. Moreover, all ranges disclosed herein are to be understood to encompass the beginning and ending range values and any and all subranges subsumed therein. For example, a stated range of "1 to 10" is to be taken to include any and all subranges between (and including) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g., 1 to 3.3, 4.7 to 7.5, 5.5 to 10, and the like. In addition, all documents mentioned herein, such as but not limited to issued patents and patent applications, are to be considered to be "incorporated by reference" in their entirety. Unless otherwise indicated, any amounts referred to are in "weight percent. The term "film" refers to a region of a coating having a desired or selected composition. A "layer" includes one or more "films". A "coating" or "coating stack" comprises one or more "layers". The term "composite TCO electrode" means a multilayer or multicomponent electrode having a transparent conductive oxide layer or material plus one or more other layers or materials. The term "free" means not intentionally added. For example, the phrase "the material is free of X" means that component X is not intentionally added to the material. However, although not specifically added, a trace amount (tramp atmosphere) of component X may be present in the material. Although silicon is not technically a metal, the terms "metal" and "metal oxide" are considered to include silicon and silicon dioxide, respectively, as well as conventionally recognized metals and metal oxides.

For purposes of the following discussion, the invention will be discussed with reference to conventional OLED devices. It should be understood, however, that the present invention is not limited to use with OLED devices, but may be practiced in other fields, such as, but not limited to, photovoltaic thin film solar cells. For other applications, such as thin film solar cells, it may be necessary to modify the glass construction as will be described later in this application.

The general structure of an OLED device 10 incorporating features of the present invention is shown in fig. 1. The OLED device 10 includes a substrate 12, an optional undercoat layer 14, a composite TCO electrode 16, an emissive layer 18, and another electrode 20. For purposes of discussion, the composite TCO electrode 16 is considered an anode and the other electrode 20 is considered a cathode. The structure and operation of conventional OLED devices will be well understood by those skilled in the art and will therefore not be described in detail.

Substrate 12 may be transparent, translucent, or opaque to visible light. By "transparent" is meant having a visible light transmission of greater than 0% up to 100%. Alternatively, the substrate 12 may be translucent or opaque. By "translucent" is meant allowing electromagnetic energy (i.e., visible light) to pass through but diffusing that energy so that objects on the side opposite the viewer are not clearly visible. By "opaque" is meant having a visible light transmission of 0%. Examples of suitable materials include, but are not limited to, plastic substrates (such as acrylic polymers such as polyacrylates; polyalkylmethacrylates such as polymethyl methacrylate, polyethyl methacrylate, polypropylene methacrylate, and the like; polyurethanes; polycarbonates; polyalkyl terephthalates such as polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, and the like; polysiloxane containing polymers; or copolymers of any of the monomers from which these are made; or any mixtures thereof); or a glass substrate. For example, the substrate may comprise conventional soda-lime-silicate glass, borosilicate glass, or leaded glass. The glass may be transparent glass. By "clear glass" is meant non-colored or non-tinted glass. Alternatively, the glass may be tinted or otherwise colored glass. The glass may beAnnealed or heat-treated glass. As used herein, the term "heat treated" means tempered or at least partially tempered. The glass may be of any type, such as conventional float glass, and may have any composition of any optical properties (e.g., any value of visible light transmittance, ultraviolet transmittance, infrared transmittance, and/or total solar energy transmittance). By "float glass" is meant glass formed by a conventional float process in which molten glass is deposited on a molten metal bath and controllably cooled to form a float glass ribbon. Non-limiting examples of glasses that can be used in the practice of the invention include

GL-35 ^TM 、

Solarphire

And

glass, all commercially available from PPG Industries inc. of Pittsburgh, pennsylvania.

Substrate 12 has a high visible light transmission at a reference wavelength of 550 nanometers (nm) and a thickness of 2 millimeters. By "high visible light transmission" is meant a visible light transmission at 550nm of greater than or equal to 85%, such as greater than or equal to 87%, such as greater than or equal to 90%, such as greater than or equal to 91%, such as greater than or equal to 92%.

Optional primer layer 14 provides device 10 with various performance advantages, such as serving as a sodium ion barrier between substrate 12 and overlying coatings. Primer layer 14 may be a homogeneous coating. By "homogeneous coating" is meant a coating in which the material is randomly distributed throughout the coating. Alternatively, primary coating 14 may include multiple coatings or films (such as two or more separate coated films). Still alternatively, primer layer 14 may be a gradient layer. By "gradient layer" is meant a layer having two or more components, wherein the concentration of the components varies continuously (or step) with distance from the substrate. For example, optional primer layer 14 may include a barrier coating such as silica, or a mixture of two or more oxides selected from oxides of silicon, titanium, aluminum, zirconium, and/or phosphorus.

Emissive layer 18 may be any conventional organic electroluminescent layer as is known in the art. Examples of such materials include, but are not limited to, small molecules such as organo-metallic chelators (e.g., alq) ₃ ) Fluorescent and phosphorescent dyes and conjugated dendrimers. Examples of suitable materials include triphenylamine, perylene, rubrene, and quinacridone. Alternatively, electroluminescent polymer materials are also known. Examples of such conductive polymers include poly (p-phenylene vinylene) and polyfluorene. Phosphorescent materials may also be used. Examples of such materials include polymers such as poly (N-vinylcarbazole) to which organometallic complexes such as iridium complexes are added as dopants.

Cathode 20 can be any conventional OLED cathode. Examples of suitable cathodes include metals such as, but not limited to, barium and calcium. The cathode typically has a low work function. For so-called "bottom-emitting" OLED devices, the cathode 20 is typically opaque. Alternatively, however, cathode 20 may be a TCO electrode or any of the composite TCO electrodes described below for the anode.

In the practice of the invention, the composite TCO electrode 16 is a multilayer or multicomponent structure. Examples of composite TCO electrode structures of the present invention are shown in figures 2-4 and described below.

The composite TCO electrode 30 of figure 2 has a first layer 32 and a second layer 34. The first layer 32 comprises a crystalline material and the second layer 34 comprises an amorphous material. The crystalline material provides higher conductivity than the amorphous material, while the amorphous material provides a smoother upper surface 36 than would be expected using only the crystalline material. This smoother upper surface 36 helps to reduce the risk of electrical shorts that may be caused by protrusions of the crystalline material of the portion that may contact the cathode 20. The material of the first and

second layers

32, 34 may be selected from one or more oxide materials, such as, but not limited to, one or more oxides of one or more of Zn, fe, mn, al, ce, sn, sb, hf, zr, ni, zn, bi, ti, co, cr, si, in, or an alloy of two or more of these materials, such as zinc stannate. The material may also include one or more dopant materials such as, but not limited to, F, in, al, P, zn, and/or Sb. Specific examples of materials for the composite TCO layer include fluorine-doped tin oxide, zinc-doped indium oxide, indium-doped tin oxide, tin-doped indium oxide, and oxides of zinc and tin (such as zinc stannate or mixtures of zinc oxide and tin oxide). In a preferred embodiment, first layer 32 includes a dopant material to enhance the conductivity of the first layer and second layer 34 does not include a dopant material. In this document, if the terms oxide material, metal oxide, dopant, etc. are used but not specifically limited, these terms should be construed according to the definitions listed in the present disclosure and this paragraph.

Another composite TCO electrode 40 is shown in figure 3. The electrode 40 includes a metal layer 42 and an amorphous transparent conductive oxide layer 44 on the metal layer 42. The metal layer 42 may be selected from, but is not limited to, the metals platinum, iridium, osmium, palladium, aluminum, gold, copper, silver, or mixtures, alloys, or combinations thereof. The amorphous conductive oxide layer 44 may be as described above. The use of the terms metal, metallic layer, etc. as used in this document and not specifically defined should be construed in light of the present disclosure and the definitions set forth in this paragraph.

Another composite TCO electrode 50 is shown in figure 4. Electrode 50 has a first layer 52, a metal layer 54, and a second layer 56. The second (outer) layer 56 is an amorphous transparent conductive oxide and the metal layer 54 is as described above. The first (inner) layer 52 may be an amorphous layer or a crystalline layer, as described above.

Another useful compound TCO electrode 60 is shown in figure 5. In this embodiment, a first layer 62 is formed on the upper coating layer 14. The first layer 62 comprises a doped metal oxide material such as any of those described above. However, the second layer 62 comprises vanadium doped indium oxide. It is believed that this structure will result in a higher light output and a lower actuation voltage. In a preferred embodiment, the first layer 62 is or includes fluorine doped tin oxide or indium doped tin oxide.

Alternative electrode structure

Figure 6 shows another composite TCO electrode 70. The composite TCO electrode 70 has a first layer 72, a metal layer 74, and a top layer 76. These layers can be deposited by room temperature sputtering without intentional heating. In a preferred embodiment, both the first layer 72 and the second layer 74 are zinc-doped indium oxide (IZO) and the metal layer 74 is silver. The metal layer 74 has a thickness in the range of 5nm to 15nm, such as 6nm to 14nm, such as 8nm to 12 nm. The underlayer 72 has a thickness in the range of 3nm to 50nm, such as 3nm to 40nm, such as 3nm to 30 nm. Alternatively, the bottom layer 72 has a thickness greater than 20nm, such as greater than 30nm, such as greater than 40 nm. Still alternatively, the bottom layer 72 may be a single layer of dielectric material (e.g., an oxide, nitride, or oxynitride material) having a high refractive index. For example, the refractive index of the underlayer 72 may be greater than the refractive index of the glass substrate 12 but lower than or equal to the refractive index of IZO in the visible spectrum. The bottom layer 72 may act as an anti-reflective coating and may also be a multi-layer stack such as a high-low-high index bandpass filter. In a preferred embodiment, the top layer 76 has a thickness in the range of 5nm to 15nm, such as 6nm to 14nm, such as 8nm to 12 nm.

Figure 7 shows another composite TCO electrode 80. The electrode 80 has a first layer 82 comprising a doped metal oxide, a metal layer 84, a primer layer 86, a metal oxide layer 87 and a further metal oxide layer 88. In a preferred embodiment, the first layer 82 comprises IZO. In a preferred embodiment, the metal layer 84 comprises silver. In a preferred embodiment, the primer layer 86 includes titanium dioxide. In a preferred embodiment, the metal oxide layer comprises zinc oxide and the further metal oxide layer 88 comprises IZO. For example, in a sputtering process, a titanium metal layer in the range of 1nm to 2nm may be deposited on the metal layer 84 in a non-reactive (low oxygen) atmosphere. A 1nm to 2nm zinc oxide layer 87 may be deposited on titanium layer 86. The zinc oxide layer 87 can be sputtered from a zinc cathode (e.g., containing up to 15 weight percent tin, such as up to 10 weight percent tin) in an oxygen atmosphere. Tin is present to improve the sputtering characteristics of the cathode. As used throughout, the term "zinc oxide" includes not only pure zinc oxide, but also zinc oxide having up to 15 weight percent, such as up to 10 weight percent, of tin oxide (from the tin in the cathode) present. Depositing the zinc oxide layer 87 in an oxygen atmosphere also results in oxidation of the underlying titanium layer 86 to titanium dioxide. Another oxide layer 88, such as an IZO layer, may be provided on the zinc oxide layer 87.

Alternatively, the metal oxide layer 87 may be removed and another metal oxide layer 88 (e.g., IZO) may be deposited directly on the primer layer 86 in two layers. The bottom layer of metal oxide layer 88 may be deposited at a high oxygen content to help convert the titanium metal of primer layer 86 to titanium dioxide. The top portion of IZO layer 88 may then be deposited using the desired optimized IZO deposition parameters of the IZO coating.

Another way to convert the titanium metal to titanium dioxide is to expose the titanium primer layer 86 to an oxygen plasma.

Figure 8 shows another composite TCO electrode 90. The electrode 90 structure includes a first layer 92 comprising a material having a relatively high refractive index. In a preferred embodiment, the material of the first layer 92 may be ITO, IZO or any other dielectric with a high refractive index. In a more preferred embodiment, the material is ITO. A metal layer 94 is on the first layer 92. Metal layer 94 may be any of the metal layers described above. In a preferred embodiment, the metal layer 94 comprises silver. A second layer 96 of metal oxide material is on the metal layer 94 and a top layer 98 of metal oxide material is on the second layer 96. In a preferred embodiment, the second layer comprises ITO and the top layer 98 comprises IZO. The top layer 98 has a thickness of less than 1 nm. Since IZO has a higher work function than ITO, the preferred embodiments result in lower actuation voltages or increased power efficiency of the OLED device.

Figure 9 shows another composite TCO electrode structure 100. In this embodiment, layers similar to those described above for fig. 8 have the same reference numbers as in fig. 8. However, the structure includes an outer layer 102 of oxygen barrier material. Examples of oxygen barrier materials include silica, alumina, or mixtures of silica and alumina. The top layer 102 has a thickness in the range of 1nm to 5nm, such as 1nm to 4nm, such as 1nm to 3 nm. When exposed to high temperatures and oxygen, such as during bending or heat treatment of the coated substrate 12, the degree of reduction of the top layer 98 (e.g., IZO) may be reduced, resulting in lower electrical conductivity. The outer layer 102 helps prevent this by protecting the IZO layer 98 from oxidation.

Figure 10 shows yet another composite TCO electrode 104 structure of the present invention having a first layer 106, a second layer 108 and a third layer 110. The first layer 106 may be a metal oxide layer, the second layer 108 may be a metal layer, and the third layer 110 may be a protective coating. In a preferred embodiment, the first layer 106 comprises zinc oxide (including up to 15 weight percent tin oxide, such as up to 10 weight percent tin oxide). In a preferred embodiment, the second layer 108 comprises metallic silver. In a preferred embodiment, the third layer 110 comprises silica, alumina, or a mixture of silica and alumina. For example, the third layer may comprise a mixture of silica and alumina, wherein the silica ranges from 40 to 90 weight percent, such as from 40 to 85 weight percent.

Alternatively, the first layer 106 and the second layer 108 may be as described above, but the third layer 110 may be a metal oxide layer. In a preferred embodiment of this alternative, the metal oxide comprises IZO.

Figure 11 shows another composite TCO electrode 120 having a first layer 122, a second layer 124, a third layer 126, and a fourth layer 128. The first layer 122 may be a metal oxide layer, such as a zinc oxide layer, such as described above with respect to fig. 10. Alternatively, the first layer 122 can be a zinc-tin alloy layer such as zinc stannate. The second layer 124 is a metal layer. In a preferred embodiment, the metal comprises metallic silver. The third layer 126 is a primer layer. In a preferred embodiment, the primer layer material comprises titanium. The fourth layer 128 is a metal oxide layer. In a preferred embodiment, the fourth layer 128 comprises zinc oxide.

Increased light scattering

In conventional bottom-emitting OLEDs, over eighty percent of the generated light is lost by the waveguide. To improve light emission, internal and external light extraction layers have been developed. However, these light extraction layers complicate the manufacturing process and affect the anode surface smoothness. In one aspect of the invention shown in fig. 12, the surface 130 of the glass substrate 12 on which the layers of the OLED device are provided (rather than the light extraction layer) is roughened to help promote light scattering, and then a planarization layer 132 is applied to present a smoother surface to the other coatings. The glass surface is roughened by any conventional method, such as mechanical grinding or chemical etching. The planarization layer 132 is then applied by conventional methods (such as CVD, sol-gel, spin-coating, spray pyrolysis, MSVD, etc.). The planarization layer 132 preferably has a similar refractive index as the overlying electrode. One example of the planarization layer 132 is an amorphous IZO having a thickness in the range of 100nm to 500nm (such as 200nm to 400nm, such as 300 nm).

It will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed in the foregoing description. Accordingly, the particular embodiments specifically described herein are illustrative only and are not limiting to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Claims

1. A method of increasing light scattering of a device having a glass substrate, comprising the steps of:

roughening the surface of the glass substrate; and

applying a planarization layer comprising amorphous indium zinc oxide IZO onto the roughened surface;

applying a first electrode on the planarization layer;

applying an emissive layer over the first electrode; and

a second electrode is applied on the emissive layer,

wherein at least one of the first or second electrodes comprises a composite Transparent Conductive Oxide (TCO) electrode comprising:

a first layer comprising an oxide material;

a second layer comprising a metallic material;

a third layer comprising an oxide material;

a fourth layer comprising zinc oxide; and

a fifth layer over the fourth layer, the fifth layer comprising IZO.

2. The method of claim 1, wherein the first electrode comprises the composite Transparent Conductive Oxide (TCO) electrode and the second electrode comprises a second composite TCO electrode comprising: the liquid crystal display device includes a first layer including an oxide material, a second layer including a metal material, a third layer including an oxide material, a fourth layer including zinc oxide, and a first layer over the fourth layer, wherein the first layer includes IZO.

3. The method of claim 1, wherein the oxide materials of the first and third layers are independently selected from one or more oxides of Zn, fe, mn, al, ce, sn, sb, hf, zr, ni, bi, ti, co, cr, si, in, or alloys of two or more of these materials.

4. The method of claim 1, wherein the third layer is amorphous.

5. The method of claim 2, wherein the third layer in the second composite TCO electrode is amorphous.

6. The method of claim 1, wherein the fifth layer is amorphous.

7. The process of claim 2, wherein the fifth layer in the second composite TCO electrode is amorphous.

8. The method of claim 1, wherein the material of at least one of the first layer or the third layer comprises one or more dopant materials.

9. The method of claim 1, wherein the metallic material of the second layer is selected from platinum, iridium, osmium, palladium, aluminum, gold, copper, silver, or mixtures thereof.

10. The method of claim 2, wherein the metallic material of the second layer in the second composite TCO electrode is selected from platinum, iridium, osmium, palladium, aluminum, gold, copper, silver, or mixtures thereof.

11. The method of claim 1, wherein the first layer comprises zinc-doped indium oxide and the third layer comprises zinc-doped indium oxide.

12. The method of claim 1, wherein the first layer comprises IZO.

13. The method of claim 1, wherein the second layer comprises silver.

14. The method of claim 1, wherein the first layer comprises a doped oxide; and the third layer comprises IZO, wherein IZO is deposited as two layers, and the bottom layer is deposited in a higher oxygen atmosphere than the top layer.

15. The method of claim 1, wherein the first layer comprises an oxide selected from ITO and IZO; and the third layer comprises ITO.

16. The method of claim 1, wherein the first layer comprises zinc oxide; and the third layer comprises alumina, silica, or a mixture of alumina and silica.

17. The method of claim 1, wherein the first layer comprises zinc oxide; and the third layer comprises IZO.

18. The method of claim 1, wherein the first layer comprises an oxide material comprising zinc and tin; and the third layer comprises titanium.

19. The method of claim 18, wherein the fourth layer further comprises tin oxide.

20. The method of claim 1, wherein the planarization layer has a thickness in a range of 100nm to 500 nm.